ANES feeling thermometer 1980 through 2016.
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Eight days ahead of the 2020 presidential election, Gallup reported that "[a] majority of Americans, 57%, say there is a need for a third, major political party. The poll results aren't an artifact of Donald Trump's presidency: "These views have been consistent since 2013."
Easier said than done, though. Duverger's Law puts it bluntly: "[T]he simple-majority single-ballot system favours the two-party system."
With more than 140 years to entrench themselves in that system and fortify their position with ballot and debate access barriers to keep competitors broke and voiceless, the Republicans and Democrats have little to fear.
Or do they?
Trump himself has quietly leaked word that he intends to remain with (and in control of) the Republican Party rather than launching a "Patriot Party" as many in his committed base, feeling betrayed by GOP cooperation in certifying the election results, had hoped and called for.
Perhaps he's meditated on the fates of three Progressive Parties created as vehicles for former "major party" contenders (former President Theodore Roosevelt in 1912, Senator Robert La Follette, Sr. in 1924, and former Vice-President Henry Wallace in 1948).
Or maybe he's just biding his time, waiting to see whether the Republican Party remains in his grip, before pulling the "Patriot Party" trigger if that looks like a plausible path back to power. Things could still get interesting.
Duverger's Law predicts a two-party system in general, not the dominance or even survival of any particular two parties.
The Whigs, split over the issue of slavery, fell on hard times and were displaced by the Republicans in the 1850s. While it's unlikely that a notional "Patriot Party" could replace the Republicans as a major party, such a Trump-centric effort might enjoy just enough support to take the GOP down with it, creating an opening for something new.
One side effect of the long Democrat/Republican "duopoly" is a sleepy centrism. If political ideology is a 360 degree circle, the "major" parties cover perhaps five degrees in the comfy "center-right" arc of that circle. As third party (and proto-Trumpian) presidential hopeful George Wallace noted in the 1960s, there's "not a dime's worth of difference" between the two in substance, despite their "polarized" presentations.
Could the (third-largest) Libertarian Party or (fourth-largest) Green Party surge into the vacuum left by a Republican fade? Decades of failure to make much headway say Americans aren't ready for that degree of change.
But if change is coming whether Americans are ready for it or not, both parties have advantages. They already hold a few elected positions (on city councils and in state legislatures, even one Libertarian congressman for a year). They're veterans at navigating difficult ballot access barriers. They're tanned, rested and ready.
As the news guys like to say, "developing."